The present invention relates to an apparatus for determining an amount of corneal ablation and a surgical apparatus for a cornea, and more particularly, to the apparatus utilized for correcting ametropia in a manner of ablating a corneal surface and varying its shape.
It is known for surgery operation, by which ametropia of an eye is corrected by a process of ablating a corneal surface (corneal stroma and the like) with a laser beam then varying its shape. In the surgical operation, both of a corneal shape (a corneal surface shape) and a refractive power of the eye to be operated (a patient""s eye) are obtained, based on which, an amount of corneal ablation necessary for correction is calculated and found. In the past, procedures for calculating an amount of corneal ablation is conducted as following.
Firstly, a corneal surface of the eye to be operated is assumed as a spherical surface or a toric surface, with this assumption, a corneal shape is estimated based on an average of a pre-operative corneal radius of curvature obtained by a corneal shape measurement. Then, an amount of corneal ablation is calculated on the assumption that a post-operative corneal shape is also to be in a shape of a spherical surface or a toric surface. This calculation is based on the values S (a spherical power), C (a cylindrical power) and A (an astigmatic axial angle) found by a subjective eye refractive power measurement and/or an objective eye refractive power measurement.
However, a cornea of a human eye does not always have a symmetric shape, such as a spherical surface, a toric surface or the like. Thus, there are some cases that a corneal shape is in an asymmetric shape such that a corneal surface shape is different in part due to irregular astigmatism or the like. In order to perform an operation for correcting ametropia adequately, it is insufficient to calculate the ablation data (i.e., data of a corneal ablation amount) composed only of a symmetric shape (i.e., a symmetric component), such as a spherical surface or a toric surface.
The present invention has been made in view of the above circumstances and has an object to overcome the above problems and to provide an apparatus for determining an amount of corneal ablation, which can calculates an amount of corneal ablation in order to perform an operation for correcting ametropia adequately, based on a corneal shape and/or an eye refractive power.
Another object of the present invention is to provide a surgical apparatus for a cornea, by which the surgical operation can be performed efficiently based on the obtained amount of corneal ablation.
To achieve the objects and in accordance with the purpose of the present invention, as embodied and broadly described herein, the present invention comprises below mentioned construction.
An apparatus for determining an amount of corneal ablation, based on which surgical operation for correcting ametropia is performed, according to claim 1, the apparatus comprises a first input unit for inputting data of a pre-operative corneal shape of a patient""s eye; a second input unit for inputting data of a post-operative corneal shape of the eye, to be estimated; an ablation amount calculating unit for calculating data of a corneal ablation amount of the eye, in a manner of calculating data of an ablation amount in a symmetric component and data of an ablation amount in an asymmetric component separately and respectively, based on the data inputted by the first input unit and the second input unit; and an output unit for outputting results calculated by the ablation amount calculating unit.
In this case, as according to claim 2, the output unit may preferably comprise a display unit for displaying the results calculated by the ablation amount calculating unit, graphically.
In this case, furthermore, as according to claim 3, the output unit may preferably comprise a sending unit for sending the results calculated by the ablation amount calculating unit, to a surgical apparatus for a cornea.
In this case, furthermore, as according to claim 4, the ablation amount calculating unit may satisfactorily calculate at least one data selected from the group consisting of a spherical component, a non-spherical component, and a cylindrical component, for use as the data of the ablation amount in the symmetric component.
Furthermore, as according to claim 5, the apparatus according to claim 1, may further comprise a corneal shape measuring unit for measuring distribution data of a pre-operative corneal radius of curvature of the eye; in which the first input unit may satisfactorily input pre-operative distribution data measured by the corneal shape measuring unit into the ablation amount calculating unit.
Furthermore, as according to claim 6, the apparatus according to claim 1, may further comprise a corneal shape measuring unit for measuring distribution data of a pre-operative corneal radius of curvature of the eye; an eye refractive power measuring unit for measuring distribution data of a pre-operative refractive power of the eye; a corneal shape calculating unit for calculating distribution data of an equivalent emmetropia corneal refractive power of the eye based on pre-operative distribution data measured by the corneal shape measuring unit and pre-operative distribution data measured by the eye refractive power measuring unit, subsequently, calculating the distribution data of a post-operative corneal radius of curvatur of the eye, to be estimated, based on the obtained distribution data of an equivalent emmetropia corneal refractive power; in which the first input unit may satisfactorily input pre-operative distribution data measured by the corneal shape measuring unit into the ablation amount calculating unit, and the second input unit may satisfactorily input pre-operative distribution data measured by the corneal shape calculating unit into the ablation amount calculating unit.
In this case, as according to claim 7, the corneal shape calculating unit may preferably calculate the distribution data of a corneal refractive power based on distribution data of the corneal radius of curvature measured by the corneal shape measuring unit, subsequently, calculating the distribution data of the equivalent emmetropia corneal refractive power based on the obtained distribution data of the corneal refractive power and the distribution data of the eye refractive power measured by the eye refractive power measuring unit; and the output unit may preferably include a display unit for displaying graphically at least one distribution data selected from the group consisting of the distribution data of the corneal refractive power, the distribution data of the eye refractive power and the distribution data of the equivalent emmetropia corneal refractive power.
Furthermore, as according to claim 8, the apparatus according to claim 1, may further comprise a correcting-refractive power input unit for inputting data of a correcting-refractive power of the patient""s eye; and a corneal shape calculating unit for calculating the data of a post-operative corneal shape, to be estimated, based on the inputted data of the correcting-refractive power; in which the second input unit may preferably input the results calculated by the corneal shape calculating unit into the ablation amount calculating unit.
Furthermore, as according to claim 9, the apparatus according to claim 1, at least one between the first input unit and the second input unit may satisfactorily comprise an input unit with which an operator inputs data.
A surgical apparatus for a cornea, which corrects ametropia by ablating a cornea of a patient""s eye with a laser beam, according to claim 10, the apparatus comprises a first input unit for inputting data of a pre-operative corneal shape of a patient""s eye; a second input unit for inputting data of a post-operative corneal shape of the eye, to be estimated; an ablation amount calculating unit for calculating data of a corneal ablation amount of the eye, in a manner of calculating data of an ablation amount in a symmetric component and data of an ablation amount in an asymmetric component separately and respectively, based on the data inputted by the first input unit and the second input unit; a first ablation unit for ablating the cornea, based on the obtained data of the ablation amount in the symmetric component; and a second ablation unit for ablating the cornea, based on the obtained data of the ablation amount in the asymmetric component.
In this case, as according to claim 11, the first ablation unit may satisfactorily comprise an irradiating optical system for irradiating the cornea with the laser beam from a laser source; and the second ablation unit may satisfactorily share the irradiating optical system with the first ablation unit.
In this case, furthermore, as according to claim 12, the second ablation unit may satisfactorily comprise a beam dividing unit for dividing the laser beam, the beam dividing unit being disposed on a light path of the irradiating optical system.
An apparatus for determining an amount of corneal ablation, based on which surgical operation for correcting ametropia is performed, as according to claim 13, the apparatus comprises a corneal shape measuring unit for measuring distribution data of a corneal radius of curvature of a patient""s eye; an eye refractive power measuring unit for measuring distribution data of an eye refractive power of the eye; a corneal shape calculating unit for calculating distribution data of an equivalent emmetropia corneal refractive power of the eye based on pre-operative distribution data measured by the corneal shape measuring unit and pre-operative distribution data measured by the eye refractive power measuring unit, subsequently, calculating distribution data of a post-operative corneal radius of curvature of the eye, to be estimated, based on the obtained distribution data of the equivalent emmetropia corneal refractive power; an ablation amount calculating unit for calculating data of a corneal ablation amount of the eye, in a manner of calculating data of an ablation amount in a symmetric component and data of an ablation amount in an asymmetric component separately and respectively, based on the results measured by the corneal shape measuring unit and the results calculated by the corneal shape calculating unit; and an output unit for outputting results calculated by the ablation amount calculating unit.
In this case, as according to claim 14, the corneal shape calculating unit may satisfactorily calculate distribution data of a corneal refractive power based on the distribution data of the corneal radius of curvature measured by the corneal shape measuring unit, subsequently, calculate the distribution data of the equivalent emmetropia corneal refractive power based on the obtained distribution data of the corneal refractive power and the distribution data of the eye refractive power measured by the eye refractive power measuring unit; and the output unit may satisfactorily include a display unit for displaying graphically at least one datum selected from the group consisting of the distribution data of the corneal refractive power, the distribution data of the eye refractive power, the distribution data of the equivalent emmetropia corneal refractive power, data of a total ablation amount, data of the ablation amount in the symmetric component and data of the ablation amount in the asymmetric component.
In this case, furthermore, as according to claim 15, the output unit may preferably comprise a sending unit for sending the results calculated by the ablation amount calculating unit, to a surgical apparatus for a cornea. dr
FIG. 1 is a view showing a schematic configuration of an optical system in the apparatus for determining an amount of corneal ablation of the preferred embodiment of the present invention;
FIG. 2 is a view showing an arrangement of photodetectors provided for a photo-receiving part;
FIG. 3 is a view showing a schematic construction of a control system in the apparatus for determining an amount of corneal ablation of the preferred embodiment of the present invention;
FIG. 4 is a view for illustrating a method of calculating a corneal radius of curvature;
FIG. 5 is a view for illustrating a method of calculating a corneal refractive power;
FIG. 6 is a view showing difference between a calculated value of a corneal refractive power obtained by measuring a corneal shape and a measured value obtained by an objective eye refractive power measurement;
FIG. 7 is a view for illustrating a method of calculating an amount of corneal ablation;
FIG. 8 is a view for illustrating a method of calculating an amount of corneal ablation;
FIG. 9 is a flow chart showing a method of calculating an amount of corneal ablation;
FIG. 10 is a view showing an example of a color map and a three-dimensional graphic display with respect to the distribution of refractive power and the distribution of ablation amount; and
FIG. 11 is a view showing a schematic arrangement of an optical system and a control system in the surgical apparatus for a cornea of the preferred embodiment of the present invention.